I'm concerned that a bottle of Fonseca 1985 that I was given a year ago is going to get ruined lying on the kitchen floor...should I drink it now or will it be ok in a house where temperatures fluctuate between 6 Celsius on a winter's night to 28 Celsius on a hot summer day?

Also what I do want to open is a Graham's 1999 Quinta or a Warre's 1997....which one would people recommend I open now?

Your Fonseca 1985 will not be ruined in that temperature range but it will evolve quicker than if it was stored at a stable temperature. If you want to hold onto it for some reason it would be a good idea to wrap it in something that will insulate it from day to day temperature fluctuations and put it in a cupboard in the centre of the house.

The Graham's 1999 will more than likely be more evolved and ready to drink than the Warre 1997 but both will benefit from a few more years in the bottle so no harm in keeping either of them.

I think the 97s are going through a bit of an awkward phase at the moment, so although I have not tried the 99 Graham thing I should probably start with that. But like Julian/jdaw1 I would find myself drawn to the Fonseca 85 on account of it being delicious.